In the control of a feed axis of a machine tool, when carrying out machining commands, impacts may be generated at parts of the machine tool due to sudden changes in the velocities of the feed axes. In order to reduce such impacts, an acceleration/deceleration control for feed axes is performed. The acceleration/deceleration control includes for example a post-interpolation acceleration/deceleration control wherein move commands, from a distributing and interpolating section of a numerical control device, are passed through an acceleration/deceleration filter, whereby a feed axis is accelerated or decelerated.
Patent Literature 1 describes an example of a post-interpolation acceleration/deceleration control for a numerically controlled machine tool, wherein acceleration/deceleration curve parameters, corresponding to cutting feed rates of the numerically controlled machine tool are determined, whereby the acceleration and deceleration for the cutting feed is controlled based on the determined acceleration/deceleration curve parameters.
Patent Literature 2 describes a numerical control device including a post-interpolation acceleration/deceleration processing section for performing post-interpolation acceleration/deceleration processing on the move commands from an interpolation processing section, and axis servo-controlling sections for performing servo control for the respective feed axes, on the basis of the move commands after the post-interpolation acceleration/deceleration processing, whereby a post-interpolation acceleration/deceleration processing section performs velocity control with allowable inward-turning amount.
Further, Patent Literature 3 describes a precision positioning control apparatus comprising a composite servo system, which includes a coarse positioner and a fine positioner, wherein the sum of the displacements of the coarse positioner and the fine positioner is detected so that the sum is compared with the displacement command, the difference of which is supplied to adjusters of the coarse positioner and the fine positioner, whereby the adjusters output signals to be input into the coarse positioners and the fine positioners, respectively.